1. Field of the Invention
This invention relates to an azimuth detecting device to be mounted in a mobile object and an azimuth detecting method.
2. Description of the Related Art
There has conventionally been known an azimuth detecting device having Global Positioning System (GPS) measuring means for receiving measuring radio waves from a GPS satellite to output first azimuth data, a geomagnetic sensor for outputting second azimuth data, storage means for storing the first azimuth data and second azimuth data in the preceding measurement timing, and correcting arithmetic means for obtaining true magnetic circle data on the geomagnetic sensor from the first azimuth data and second azimuth data in the preceding and present measurement timings so as to correct the geomagnetic sensor on the basis of the true magnetic circle data (see, for example, Japanese Patent Application Publication No. 5-18770 (JP-A-5-18770)).
The azimuth detecting device described in JP-A-5-18770, however, cannot correct the outputs of the geomagnetic sensor accurately because a gain fluctuation in the geomagnetic sensor and a fluctuation in geomagnetic declination and inclination are not taken into consideration.